Polystyrene (PS) is a thermoplastic plastic formed by the free radical polymerization of styrene monomers. It can be regarded as a “transparent, brittle and inexpensive general-purpose plastic” - it forms linear molecular chains by opening the double bonds of styrene, thus possessing excellent optical transparency (with a light transmittance of up to 90%), good electrical insulation, extremely low water absorption, and excellent processing fluidity (easy to injection mold, extrude, and foam), but is brittle, has poor impact resistance, and is not resistant to solvents. Polystyrene is widely used in disposable tableware (transparent cups, fast food boxes), CD/DVD disc cases, stationery rulers, cosmetic containers, food packaging trays, and expanded polystyrene (EPS, i.e., foam boxes, cushioning pads), etc., in situations that require transparency, low cost, and low requirements for impact strength.